Calibration and reliability of the Periotron 6000 for individual gingival crevicular fluid samples

Abstract

The Periotron 6000 fluid analyser has become widely used as a diagnostic tool for a variety of oral diseases and recent work has questioned its reliability. This paper investigates for the first time, the detailed calibration curves of 2 Periotron 6000 machines across a range of 23 different fluid volumes. Within and between machine reliability is analyzed and the shape of the calibration line determined. The measurement errors incurred by using a single fluid sample, as opposed to mean values of triplicate samples are also determined. We conclude that there are 3 sections to the calibration line, 2 linear and a quadrilateral zone, and that 2 separate regression equations should be used; from 0-0.1 microliter and from 0.1-1.0 microliter. Within machine calibration errors were only 3.2 +/- 7.5%, but values for volumes below 0.2 microliter were as high as 18.7%. Using a single fluid sample rather than mean values of multiple samples, incurred a further 4 +/- 4% error, which was as high as 7% for volumes lower than 0.12 microliter. Whilst significant differences in volume reading existed between different machines (p < 0.0004) and between the same volumes of different fluids (p < 0.00001), individual Periotron calibrations were extremely reproducible and reliable. We conclude that the Periotron 6000 is a reliable and convenient instrument for measuring fluid volumes greater than 0.2 microliter. For volumes lower than 0.2 microliter errors in measurement may be too high for some investigations, but this is likely to be due to problems with evaporation and with measurement technique, rather than errors directly due to the Periotron itself. Finally, for optimum accuracy, the digital display should be re-set to zero after each sample is measured.

Critical steps in electronic volume quantification of gingival crevicular fluid: the potential impact of evaporation, fluid retention, local conditions and repeated measurements

“…Further, standardization of the room conditions would not always be feasible in the clinical setting and, therefore, results would not pertain to clinical environment (38). Thus, to minimize evaporative losses, we support the previous studies recommending immediate transfer (within 0–2 s) (31, 45) of sample strips to the device, standardization of room conditions (whenever possible) (16, 31) and placement of the sample strips within sealed containers (40).…”

“…Evaporation, due to inevitable delay in measuring the strip, was listed among the disadvantages of the staining techniques and in methods where wet strips are weighed (2). The measurement technique and problems with evaporation, rather than Periotron 6000 ® itself, were shown to produce errors, especially for volumes < 0.2 µl (mean error due to evaporation 18.7%), and it was calculated that 0.1 µl of GCF would only have to lose 10 nL through evaporation in order to incur a 10% error, and evaporation was also accounted as the main source of within machine variances (31). In another study, the range of error due to evaporation was reported to be between 5% and 11% (10) and evaporative errors were especially considered to be crucial for sites harbouring only small amounts of GCF (10, 31, 34).…”

“…The possibility and the extent of the retained fluid within the counterparts of the device were analysed by use of two different test fluids with different physiochemical properties, human serum and distilled water. To obtain the serum samples, human venous blood, which was allowed to clot, was centrifuged at 3000 g for 5 min (31). Paper strips were provided with either distilled water or human serum for two different test volumes, 0.1 µl and 0.6 µl, representing rather smaller or larger volumes, and strips with known amounts of test fluids were immediately transferred between the counterparts of the device for volume determination.…”

Estimation of Bone Loss Biomarkers as a Diagnostic Tool for Peri‐Implantitis

“…The sampled fluid volume in the strip was measured using a device for impedance measurement †† calibrated as reported previously, 38 and the paper strips were then inserted in microcentrifuge plastic tubes containing 0.5 mL sterile phosphate‐buffered saline. After 10 seconds of vortexing, the samples were centrifuged for 5 minutes at 3,000 × g to separate the cells and debris, and then the paper strips were removed.…”

Application of the Checkerboard Immunoblotting Technique to the Quantification of Host Biomarkers in Gingival Crevicular Fluid

“…Samples visibly contaminated with blood were discarded. GCF volume was determined using a Periotron 8000® ##, calibrated following the protocol described by Chapple et al18. The samples were immediately placed in Eppendorf tubes containing 150 µl of elution buffer [PBST (0.05% Tween 20 in phosphate-buffered saline)], transported to the laboratory and stored at −80°C until assayed.…”